Electrical connectors



May 28 1958 E. A. r-:RlKssoN 3,386,069

ELECTRICAL CONNECTORS Filed Sept. 9, 1965 2 Sheets-Sheet 1 zNVENToR.EEA/57' .4. Eem/ssen l I l l l| A QE/ d A n 7 5 6 5 4 m .d l 4 5 8 o w.m 9 8 889% a/ w U m United States Patent O 3,386,069 ELECTRICALCQNNECTORS Ernst A. Eriksson, 41 Preston Road, Lexington, Mass. 02173Filed Sept. 9, 1965, Ser. No. 486,066 6 Claims. (Cl. 339-7) ABSTRACT FTHE DISCLOSURE An electrical connector having a pair of electricalcontacts, one being rotatable and having a surface matching a path ofrevolution concentric with the axis of rotation thereof, and a resilientpack of iilamentary conducting material in electrical connection withsaid contacts, said pack having its surface, in contact with the surfaceof said one contact, matching the surface of said one contact.

This invention relates to new and improved means for establishingelectrical contact between members movable relative to each other,especially relatively rotatable members.

The existing counterparts to the invention are conventional collectorrings or slip-rings and their brushholders. Their general installationcan become quite massive and inconvenient, requiring considerable careand maintenance particularly due to oxidation and rapid wearing of thecontact surfaces and being vulnerable because of their awkwardspacedemanding conguration.

The novel device of the invention will perform as well as or better thanany conventional device while at the same time providing a connectorthat is simpler, more compact, maintenance-free and convenient toinstall thereby affording greater equipment desi-gn flexibility. It isarc-proof, totally enclosed, has extended contact with a matingconductive surface for enormously greater current capacity with smallsize, and will operate at high speeds, create little or no electricalnoise and has long wearing characteristics.

The invention features the use of a resilient pack of iilarnentaryconducting material in a cavity that exposes a surface of revolution ofthe pack to a mating surface of revolution of a movable electricalcontact. `Both the movable Contact and another electrical contact thatengages another portion of the pack are connected to members .movablewith respect to each other, thereby providing an unbroken electricalconnection between them. The mating surfaces of revolution arepreferably 360 closed surfaces and may be cylindrical about a centralaxis or in the form of parallel engaging rings about a central axis. Inone form of the invention such surfaces cornprise surfaces of revolutiondescribed by a curved line revolved about an axis and are preferablyspherical. The invention contemplates multi-circuit units with a packand mating conducting surface supplied for each circuit as well asuniversal joint type relatively movable contacts.

Other objects, features and advantages will appear from the followingdescription of presently preferred embodiments of the invention, takentogether with the annexed drawings, in which:

FIG. 1 is a vertical sectional View of a spindle type ICC movable rotaryheads having cylindrical mating surfaces;4

FiG. 2 is a cross-sectional view on line 2-2 of FlG. l;

FIG. 3 is an elevation, partially in section, of a modication employinga collar type arrangement of a rotary connector of the inventionsurrounding a shaft;

FIG. 4 is a vertical sectional view of a further modilication comprisinga spindle type rotary connector in which the mating surfaces ofrevolution lie in vertically spaced horizontal planes;

FIG. 5 is an elevation of a spindle type rotary connector similar tothat of FIG. 1 but Iwith three instead of only two circuits;

FIG. 6 is a vertical sectional view of a still further modified rotaryconnecter for coaxial conductors, exible or rigid, rotatable relative toeach other;

FIG. 7 is an elevation partially in section of a universal joint typeconnector useful in connecting a rotatable coaxial conductor tostationary members with a universal joint feature; and

FIG. 8 is a view on line 3 8 of FIG. 7.

Referring now rst to FIG. 1, it should be noted that all parts exceptnuts, bolts and screws are cylindrical about the central, vertical axis,as indicated in FIG. 2.

The body of the rotary connector shown in FIG. 1 is generally designatedby the numeral 1G. The two rotary heads are 11 and 12.

The body 1G of the rotary connector comprises electrically insulatingbase piece 13, electrically conducting piece 14, insulating piece i5',conducting piece 16, insulating piece 17 and conducting piece 13.Keeping all of the pieces except piece 13 of the body 10 together is theconducting nut and bolt 19.

Fitting onto piece 1-5 of the body 19 is an insulating cap 20. Piece 13is secured to piece 18 by conducting screw 21 and lock nut 22 and topiece 14 by conducting screw 23 and lock nut 24.

The base 13 has mounting roles 25 and a hole 26 to allow adjustment ofnut and bolt 19.

The body 19 is designed to be mounted on a support which may bestationary or rotatable. The outer rim of piece 17 is meant to keeprotary heads 11 and 12 in place. Piece 17 also acts to separate therotary heads, both mechanically and electrically.

yBecause the rotary heads 11 and 12 are substantially identical, onlyhead 11 will be described in detail.

The principal member making up the head 11 is the insulating retainingpiece 27. Conducting piece 28 is press tted therein and connected toconducting screw 29 and nuts 39 and 31. Filling the cavity formed bypieces 27 and 28, which together form a holder open at one side, andpiece 16, is the conductive pack 32. This pack is a mass ofloosely-woven resilient copper, bronze or aluminum cloth ofinterconnected strands which conducts electricity and has a desirablespringback characteristic in its packed attitude, insuring near contactat all times.

In operation, an electrical connection is made to terminal screw 29.With the aid of piece 28 electrical contact is continued to theconductive pack 32. Whether actually rotating or not, the conductivepack makes continuous electrical contact with the outer cylindricalsurface of member 16, secured to the stationary body 10. The electricalpath continues from piece 16, conducting nut and bolt `19, piece 14 toterminal 23, to which an outside connection may be made. Thus a goodelectrical circuit is established between terminal 29, rotatable withrespect to the body 10, and terminal 23, mounted on the body 10. Theconstruction and mode of operative of rotary head 12 is the same exceptthat the electrical path is along piece 18 to terminal 21. Thiselectrical path is insulated from that associated with rotary head 11.Meclranically, the two rotary heads can rotate with respect to each aswell as to the base, if desired, and even in opposite directions.

FIG. 3 illustrates an embodiment of `the rotary connector of theinvention which comprises a collar, one part 41 of which may rotateindependently of a shaft 40 on which it is tted, the other part 42 ofwhich is secured to and rotates with the shaft 40. In FiG. 3 tall piecesexcept nuts, screws and bolts are cylindrical and concentric about thecentral, horizontal shaft axis.

The principal member of part 42 is an electrically insulating piece 43,secured to the shaft 40 by a screw 44. The ring 45 maintains the desiredrelationship between parts 41 and 42. The member 43 forms two cavities,the outer one of which contains electrically conducting piece 46 inconductive engagement with conducting headless screw 47 carrying locknut 48 and connecting nut 49. This cavity contains a conductive pack 50of the kind described in connection with FIG. l.

The principal member of part 41 is insulating piece 51, rotatable withrespect to the shaft 40. Arranged opposite piece 46 of part 42,conducting ring 55 is bonded within the cavity. Headless screw 52, locknut 53 and connecting nut 54 provide an external electrical terminal`for the ring 55.

Also within the members 41 and 42 is a similar inner circuit havin-gconducting terminal screw 56, conducting piece 57, pack 58, conductingpiece 59 and conducting terminal screw 60.

In operation, pack 50 provides an electrically conductive path betweenparts 46 and 55 which may move relative to each other. This outercircuit is completed between the external terminals 47 and 52; theother, inner, electrical circuit is similarly completed through terminallS6, piece 57, pack 58, piece 59 and terminal 60. In this ernbodiment,terminal screws 52 and 56 are mounted on the same insulating piece 51,and terminal screws 47 and 60 mounted on the same piece I43, so thatterminals 52 and 56 cannot 4move relative to each other and neither canterminals 46 and 60. The entire unit, if desired, can be secured to astationary support by a bracket indicated by the dotted lines.

FIG. 4 illustrates a spindle type rotary connector similar to that shownin FIG. l except that in the former embodiment there were separaterotary heads capable of rotating relative to each other, each with itsown terminal. In the present embodiment two terminals are connected toone rotary head.

In FIG. 4 Where again all pieces except nuts, screws and bolts arecylindrical and concentric about 'the central, vertical axis, the mainbody is designated generally by the numeral 70 and the rotary head bythe numeral 71.

The body 70 comprises electrically insulating piece 72, electricallyconducting piece 73, insulating piece 74 and conducting pieces 75 and76. Keeping all of the body members except piece 72 together and joiningthe rotary head 71 to them is conducting nut and bolt 77.

An insulating cap piece 73 lits on the top of piece 76.

Securing piece 72 to piece 75 is conducting screw 79 with lock nut 80;securing piece 72 to piece 73 is conducting screw 81 with lock nut 82.

Similarly insulating member 83, like member 27 in FIG. 1, is providedwith conductive liners 8S and 9:1 press tted into the two cavities whichit provides. The conducting screw 85, with its nuts 86 and 37, in theupper section, penetrates through to the pack 84 and is connected to theliner 91 by soldering for example. During rotation the pack 84 keepselectrical contact with piece 76. The electrical path continues frompiece 76 to nut and bolt 77, piece 73 and terminal screw 81 where anoutside connection may be made. The lower section of the head has asimilar path from screw 89 through pack 90 and piece 75 to terminalscrew 79. Terminal screws 85 and 89 cannot move relative to each otherbecause of their attachment to piece 83.

FIG. 5 is a side view in elevation of a spindle type rotary connectorsimilar to the one shown in FIGS. 1 and 2 except that provision has beenmade for three electrical paths instead of two. The base is designatedby the numeral 100. The three rotary heads are designated 101, 102 and103, The screws, or outside terminals, associated with these rotaryheads are designated 104, 105 and 106, respectively. The screw terminals107, 1108 and 109 in the base are each the terminus of an electricalpath associated with each of the rotary terminals 101, 102 and 103.Which base terminal is associated with a rotary terminal depends, otcourse, on the internal structure selected which is essentially similarto that of FIGS. 1 and 2 tand for that reason has not been repeated.

FIG. 6 illustrates a rotary connector making an electrical connectionbetween two coaxial conductors, rigid or llexible, that may rotaterelative to each other.

The upper coaxial conductor is designated generally as 110, the lower as111 and the connector as 112. The inner conductor 113 of cable 110 iscentered within the insulating portion 114 and the outer conductingsheath I115. Corresponding parts of cable 111 are designated as 116, 117and 113 respectively.

All pieces of the connector are cylindrical and concentric about acentral, vertical axis.

The connector 112 is composed of electrically conducting piece '119 withthreads 120, electrically insulating pieces `121 and 122, conductingpiece 123 and insulating piece 124 with threads 125 to match those ofpiece 119. The cavity formed by pieces 121 and 122 is filled with aconductive pack 126 of the kind previously described, and the cavityformed by piece 119 and pieces 121 and 122 by a conductive packdesignated `127.

Each coaxial conductor has been cut perpendicularly to its main axisexcept for the inner conductor 113 or 116 which extends beyond.

In operation, both conductor sheaths and 118 extend into the cavityformed by piece 119. There they both contact the conductive pack 127which surrounds them. Inner conductor 113 extends past-piece 122 andinner conductor 116 extends past part of piece 121 into the cavityformed by pieces 121 and 122 where they both con. tact conductive pack126 which similarly surrounds them. As inner conductors 113 and 116rotate with respect to each other they continue to make electricalcontact through the pack 126. The same is true of conductive pack 127and outer conductors 115 and 118.

FIGS. 7 and 8 illustrate `a universal joint type application of thenovel conductive pack effect. Not only full rotation but any movement ina 75 conical area is allowed by this embodiment.

A coaxial conductor is designated generally as 130. The connector isdesignated by the numeral 131. The conductor 130 has an inner conductor132 centered within an insulating portion 133 and a conducting sheath134.

All pieces of the connector except nuts, screws and bolts are concentricabout a central vertical axis.

Electrically conducting piece 135, spherically shaped, grasps theconductor 130 and moves with it relative to the adjacent parts of theconnector 131. The conductor 130 is cut perpendicularly to its axis andextends just past the outer portion of the connector 131 except for theinner conductor 132 which continues in until it is connected tospherical inner conducting piece 136. Piece 136 also moves with respectto the adjacent parts of the connector 131.

The remaining pieces are all joined together and form the balance of theconnector 131. None of these pieces may move relative to each otherexcept the conductive packs 137 and 138.

The upper portion of the connector 131 is insulating piece 139 withthreads 140. The lower portion is insulating piece 141 with threads 142to match those of piece 139. Conducting bolt 143 with lock nut 144 andcontact ring 145 and terminal connecting nut 146 provide an electricalpath from the outside to the annular conductive pack 138 (FIG. 8).

Insulating piece 147 contains the inside assembly. It is cut in halfalong the plane of the sectional view and joined with the aid of bolts(not shown) through holes 148. Contained within the upper portion ofpiece 147 is spherical conducting piece 136 and a conductive pack 137.Conducting bolt 149 provides the eletcrical connection from pack 137 tothe outside. A terminal nut 150 aids outside connection.

The bottom protruding portion of piece 147 is threaded so that it may besecurely fastened by nut 151.

'In operation, even while piece 136 may move relative to the connector131 electrical contact with the conductive pack 137 continues andthrough the pack to the bolt 149 providing an outside terminal. The sameis true of piece 135, pack 138 and bolt 143.

The uses which may be made of various forms of the invention are toonumerous to list and only some of them will be referred to, it beingunderstood that those skilled in the electrical and electronics artswill undoubtedly nd the invention useful for many additional purposes.In industry there are innumerable systems requiring the transmission ofcurrent or electrical signals between a nonmoving and a moving member orbetween two moving members, usually involving a rotating system. Theinvention makes possible such transmission eiectively while at the sametime eliminating interference from intermittent or irregular contactwhich is common to many known systems and it also .prevents escape ofsignals and entry of unwanted signals into the system. Examples includeradar antenna Systems; missile guidance equipment; manned centrifugesused in the space program; scanning devices; A.C. electric motors of allsizes, kinds and shapes; directional finders; probes; Oscilloscopes;controls; r.p.m. read-out devices, and so on. The connector is of coursenon-arcing and hence explosion proof.

Another large eld of use is in the transmission between relativelymovable members or systems of high power utilizing either high currents,high voltage, or both. Examples include: pantagraph operations (i.e.positioning, etc.); mobile apple picker units; electric cable reels;heated rolls (for calendaring, etc.); moving illuminated signs; machinetools; moving amusement park equipment (i.e. ferris wheels andcarousels); moving searchlights and beacons, to name but a few.

In the iield of home appliances the potential uses are virtuallyunlimited since the invention makes possible the much sought-aftercompletely relaxed strain-free attitude of connectors, cable cords andconnections to moving or portable appliances so as to prolong life andeliminate frequent replacement or repair and the danger from frayed orbroken electrical cords. Some include: power operated hand tools of allkinds (drills, saws, etc.); electric irons, vacuum cleaners, blenders,cooking utensils, etc.; telephone hand sets; laboratory equipment andall kinds of test equipment.

In the eld of coaxial conductors, particularly those of a heavy nature,subject to twisting, torque may be eliminated by the insertion in thesystem of a connector of the type shown in FIG. 6. Where 90 elbows arerequired subject to rotation or twisting an adaption of the embodimentof FIGS. 7 and 8 may be advantageously employed. Universal joints of anelectro-mechanical nature likewise form a natural field of exploitationfor the same embodiment, whether the movement be oscillating,rotational, or conical, individually or in any combination.

Properly oriented with respect to the force applied the novel connectorwill withstand infinitely greater centrifugal or G yforces thanconventional slip rings and brushes since the force will only serve toproduce better rather than poorer contact by compacting the material ofthe conductor pack against the 360 mating contacting surface. Suchforces tend to ing the contacts apart in conventional configurations,rather than together, as is well known.

Another advantage inherent in connectors employing the invention is thesmall voltage drop across the moving contacts because of the largevolume of conductive material present and the 360 contact. This is animportant consideration where sensitive devices are being used or wheremaximum power must be transmitted (i.e. with minimum loss). As appliedto heated equipment, this is also true, for the new connector will notsuffer loss of conductance with increased temperature as is true ofconventional slip rings and brushes. Nor can the connector of theinvention deteriorate as to conductivity due to wear or accumulation ofdirt or loss of any spring tension as is commonly experienced withconventional equipment.

I have herein attempted to set forth the best mode contemplated by mefor carrying out the invention. Modifications, changes, and additionaluses will no doubt occur to those skilled in the art and it is notintended that the scope of the invention be limited by the specificembodiments shown and described or the specific end uses enumerated, butonly by the proper scope of the appended claims.

I claim:

1. In a rotatable electrical member having a cavity and a pair ofelectrical contacts, each of said contacts having a surface exposed tosaid cavity, one said contact rotatable in said member and the saidsurface of said one contact matching a path of revolution concentricwith an axis of rotation of said one contact, that improvementcomprising:

a resilient pack of interconnected loosely woven strands of tilamentaryconducting material conned within said cavity in electrical contact withsaid surface of said one contact, said pack having one pack surface,adjacent and in contact with said one contact, matching said path ofrevolution and said surface of said one contact.

2. The improvement claimed in claim 1 in which said one contact and saidpack surfaces are endless, closed surfaces.

3. The improvement claimed in claim 2 in which said one contact and saidpack surfaces are cylindrical about a longitudinal axis of rotation.

4. The improvement claimed in claim 2 in which said one Contact and saidpack surfaces are radially extending, annular rings about a longitudinalaxis of rotation.

5. The improvement claimed in claim 2 in which said one contact and saidpack surfaces are segments of spheres about the point of intersection ofa plurality of axes of rotation.

6. In a multi-circuit rotatable electrical member having a plurality ofcavities and a like number of pairs of electrical contacts, the contactsof each pair each having a surface exposed to one of said cavities, onesaid contact of each pair rotatable in said member, and said surface ofsaid one contact of each pair matching a path of revolution concentricwith an axis of rotation of said one contact, that improvementcomprising:

a resilient pack of interconnected loosely woven strands of lamentaryconducting material confined within each said cavity in electricalcontact with said surfaces exposed to said cavity, each said pack havingone surface, adjacent and in Contact with said one contact in saidcavity, matching said path of revolu- 7 8 tion and said surface of saidone contact in said 2,808,574 10/ 1957 Kelly 339-8 cavity. 2,837,7236/1958 Krantz et al 339-5 3,105,728 10/1963 Seeloi 339-5 References Cmd3,195,094 7/1965 Mohr 339-8 UNTTED STATES PATENTS 5 FO PA E S 1,762,4226/1930 Rohrdanz 339-8 REIGN NT 2,173,325 6/1939 Alexander 339-5 302,01212/1928 Great Brltam. 2,387,015 10/1945 Gilbertson 339-8 562,438 5/1957Italy 2,433,938 1/1948 Varner 339-5 519933 8/1950 Rouault 339 7 X 10MARVIN A. CHAMPION, Pl'lmary Examiner.

2,652,546 9/ 195 3 Chrstner 339-7 P. TEITELBAUM, Assistant Examiner.

